For conventional transmission controls, the gear ratio changes are determined by means of a shifting characteristic line from the actual vehicle straight-line speed and the actual accelerator pedal position or throttle flap position. This determination of the shifting characteristic line of an automatic transmission control is purposeful in the normal case but can lead to unwanted shifting in special driving and environmental situations. Such special situations can, for example, be caused by the different types of drivers and/or by different driving or environmental situations to which the vehicle is subjected. As soon as additional criteria for detecting such cases are applied, in addition to the throttle flap position and vehicle straight-line speed, further degrees of freedom result for optimizing the gear ratio of the automatic transmission in the form of adaptive control.
Such systems for adaptive transmission control are, for example, disclosed in the following: U.S. Pat. Nos. 5,025,684 and 5,157,609; an article of A. Welter et al entitled "Die Adaptive Getriebesteuerung fur die Automatikgetriebe der BMW Fahrzeuge mit Zwolfzylindermotor" published in ATZ, no. 94 (1992) 9, starting at page 428; and, the article of A. Welter et al entitled "Die Adaptive Getriebesteuerung fur BMW-Automobile" published in ATZ, no. 95 (1993) 9, starting at page 420. These articles describe the selection of different shifting characteristic lines in dependance upon recognized types of driver and/or in dependance upon various driving and environmental situations. In addition to the accelerator pedal or throttle flap position, the following are especially also detected: the vehicle straight-line speed (that is, the speed of the vehicle in the forward direction of movement of the vehicle), the vehicle transverse acceleration, the vehicle straight-line acceleration, the vehicle straight-line deceleration and the engine rpm. These quantities are assembled via a number of characteristic fields and/or logic functions to form a characteristic variable. In this way, the driving activity or the driving and environmental situations are determined, if required, by means of filtering. These then function to select a shifting program from a plurality of shifting programs which lie between a shifting program optimized for consumption and a shifting program optimized for power.
With such controls, the switching characteristic of an electrically hydraulically controlled automatic shifting transmission can be continuously adapted to the driving style of the driver or to a traffic situation which is just then present. The complexity for a plurality of characteristic fields or logic functions (for example, for obtaining the driving activity and/or driving situation) and a plurality of shifting programs is very great. It is known to utilize simple evaluation methods or fuzzy logic to reduce the complexity for determining a driving-activity related variable. In such systems, the problem which results from the plurality of different shifting programs remains.